// http://ross.posterous.com/2008/08/19/iphone-touch-events-in-javascript/
function touchHandler (event) {
  const touches = event.changedTouches,
    first = touches[0];
  let type = '';
  switch (event.type) {
  case 'touchstart': type = 'mousedown'; break;
  case 'touchmove': type = 'mousemove'; break;
  case 'touchend': type = 'mouseup'; break;
  default: return;
  }

  // initMouseEvent(type, canBubble, cancelable, view, clickCount,
  //  screenX, screenY, clientX, clientY, ctrlKey,
  //  altKey, shiftKey, metaKey, button, relatedTarget);

  const simulatedEvent = document.createEvent('MouseEvent');
  simulatedEvent.initMouseEvent(type, true, true, window, 1,
    first.screenX, first.screenY,
    first.clientX, first.clientY, false,
    false, false, false, 0/* left */, null);
  if (touches.length < 2) {
    first.target.dispatchEvent(simulatedEvent);
    event.preventDefault();
  }
}

document.addEventListener('touchstart', touchHandler, true);
document.addEventListener('touchmove', touchHandler, true);
document.addEventListener('touchend', touchHandler, true);
document.addEventListener('touchcancel', touchHandler, true);
